Monitoring of plasmid dissociation and pathogenic potential amongYersinia enterocolotica andYersinia pseudotuberculosis during storage of refrigerated pork meat

Abstract

To determine the pathogenic potential of Yersinia in pork meat samples, different strains of Yersinia enterocolitica and Yersinia pseudotuberculosis were inoculated on pieces of raw pork meat samples and exposed to +4 °C and -20 °C for 90 days. The effect of temperature, pH, total bacterial number, and inoculation dose of meat samples on virulence plasmid dissociation among different serotypes of Y. enterocolitica and Y. pseudotuberculosis was monitored by using modified cultural media and confirmed by PCR assay and in vivo mouse model. In comparison with the initial dose of contamination, Yersinia cells from the less pathogenic serotypes (O:3 and O:9 of Y. enterocolitica) survived better than the high pathogenic serotypes of Y. enterocolitica O:8 and Y. pseudotuberculosis O:3. Maximal rates for plasmid dissociation were found among the cells of the less pathogenic serotypes O:3 and O:9 of Y. enterocolitica. In parallel, at each time point highly virulent phenotypes of Yersinia were proved by direct PCR assay including detection of both chromosomal (ail) and plasmid (virF) genes. The real pathogenic potential of Yersinia cells occurred after plasmid dissociation during long time cold storage was confirmed in a newly designed mouse model mimicking the immunosupression status of humans. Therefore, the impact of refrigeration temperatures differs for the Yersinia serotypes and modulates their pathogenic potential resulting in a risk factor for human health.

Viability of The Isolated Yersinia enterocolitica Strains from Damietta Cheese and Ice Cream at Different Refrigeration and Freezing Temperatures

“…Its ability to grow at low temperatures is owing to the nature and structure of the plasma membrane which can undergo a phase of transition from a liquid crystalline state to a rigid gel when exposed to low temperature. In addition to the relatively resistance of its enzymatic systems to freezing and remain active even at -30 o C (Iliev andNajdenski, 2008 andRakesh, 2007).…”

Isolate Specific Cold Response of Yersinia enterocolitica in Transcriptional, Proteomic, and Membrane Physiological Changes

“…For example, strains with various serotypes survived differently at 4 • C in soil and river water (Tashiro et al, 1991). The impact of low temperatures on the survival of Y. enterocolitica strains differs when inoculated on raw pork samples at 4 and −20 • C for 90 days (Iliev and Najdenski, 2008).…”